[370] The origin of
the Boeing B-52 Stratofortress can be traced to design studies of
a replacement aircraft for the very large propeller-driven Convair
B-36. Too complex to be traced here are the many interwoven facets
of these studies. An interesting history of the Boeing B-52 may be
found in a book by Walter J. Boyne entitled Boeing B-52
A Documentary History
(published by Jane's Publishing
Co., 1981). First flight of the prototype B-52 took place on April
15, 1952, and now after more than 30 years, the type still serves
as a major element of this nation's nuclear deterrent force. No
more impressive tribute to the basic soundness of an aircraft
design could be found. After a total production run of 744 units,
the last B-52 was delivered in October 1962. The aircraft first
became operational in the Strategic Air Command in June
1955.

The B-52 was produced in models A through
H. A three-view drawing of the B-52G is shown in figure 12.8;
photographs of a B-52H are presented in figures 12.9 and 12.10.
The landing-gear arrangement is illustrated in figures 12.11 and
12.12; refueling of a B-52 by a Boeing KC-135 is illustrated in
figure 12.13. As with so many successful aircraft, the term B-52
encompasses a whole family of generically related types of similar
appearance but with major and minor differences in systems,
equipment, and performance. Physical and performance data are
given in table
VI for the last version of the
aircraft, the B-52H.

As seen in figure 12.8, the basic
configuration of the B-52 is similar in concept to that of the
B-47. The shoulder location of the sweptback wing, wing-mounted
engines, and bicycle landing gear are all reminiscent of the
earlier aircraft. As shown in table VI, however, the B-52 is a much larger and heavier
aircraft than its predecessor.

The wing of the B-52 has a sweepback angle
at the quarter chord of 35°, an aspect ratio of 8.56, and
airfoil thickness ratios that vary from 14 percent at the root to
8 percent at the tip (these thickness ratios are only
approximate). Fowler-type single-slotted flaps for lift
augmentation are located at the trailing edge of the wing. These
large flaps may be seen in figure 12.11. Hydraulically actuated
spoilers are used for lateral control and, in the symmetrically
deployed configuration, assist in flight-path control during
landing approach and braking during rollout. On the A through F
models of the aircraft, lateral control was provided by the
spoilers working in conjunction with conventional ailerons. Wing
area of the B-52 is 4000 square feet, nearly three times larger
than that of the B-47.

Elevators and rudder, both of small chord,
are used for longitudinal and directional control. An aerodynamic
servotab system actuates these surfaces in response to the pilot's
control inputs. A hydraulically adjustable stabilizer is used for
trimming the aircraft longitudinally. This surface has sufficient
aerodynamic power to rotate the aircraft on takeoff-, the B-47,
which did not have an adjustable stabilizer, could not be rotated
and was flown off the runway at the attitude angle imposed....

....by the bicycle landing gear. The far
forward position of the aircraft center of gravity relative to the
rear bogie requires an aerodynamic moment for rotation much larger
than could be provided by the small, manually actuated
elevators.

The landing gear of the B-52 is of the
same bicycle arrangement as employed on the B-47 but has four
two-wheel bogies instead of the two bogies used on the earlier
aircraft. Details of the landing gear are shown in figures 12.11
and 12.12. As compared with their location on the B-47, the
outrigger wheels are positioned much nearer the wingtip on the
B-52. (Compare photographs in figs. 12.11 and 12.6.) An
interesting feature of the B-52 landing gear greatly eases the
problems posed by crosswind landings. Both the front and rear
bogies can be set at angles of as much as 20° to either side
of the straight-ahead position. In a crosswind landing,
consequently, the aircraft can be headed directly into the wind
while rolling down a runway not aligned with the wind. In figure
12.11, the gear is shown set for a crosswind landing. Only the
front bogies are used for steering on the ground. Although the
wing spoilers obviate the need for an approach chute on the B-52,
a 44-foot-diameter braking chute is provided for deployment in the
landing rollout. The aircraft is not equipped with JATO units for
use on takeoff.

All production models of the B-52 have
been powered by eight engines located in pairs of two in four
nacelles. All four of the nacelles are attached to the wings by
sweptforward pylons that extend below the lower surface of the
wing. Except for the B-52H, all models of the aircraft have been
equipped with a version of the Pratt & Whitney J-57 turbojet
engine of about 13 750 pounds thrust. A fan version of the J-57,
the TF-33 of 17 000 pounds thrust, powers the B-52H. This engine
is essentially similar to the Pratt & Whitney JT3D turbofan
that powers the Boeing 707 and Douglas DC-8 commercial airliners.
Much improved performance, particularly range and takeoff field
length, resulted from application of the turbofan engine to the
B-52.

The B-52 is normally manned by a crew of
six. Two pilots are seated side by side near the nose in a manner
similar to a commercial transport. (The two prototype aircraft had
the pilots seated in a tandem arrangement similar to that of the
B-47. This cockpit configuration can be seen in the photograph of
the XB-52 shown in fig. 12.11.) On a lower deck beneath the
pilots' compartment are seated the navigator and radar navigator.
Behind the pilots on the upper deck are seated the electronic
warfare officer and, on the G and H models, the gunner who
remotely controls the guns located in the tail. On earlier
versions of the aircraft, the gunner was physically located in the
tail end of the [376] fuselage. Movement of the gunner from the tail to
a position behind the pilots removed this unfortunate individual
from an isolated location that in turbulent air promised a ride
similar to that of a high-speed roller coaster. Several types of
tail guns have been employed on different versions of the
aircraft. A 20-mm six-barrel rotary cannon is installed in the
tail location on the G and H models of the B-52.

All crew stations are pressurized, heated,
and air-conditioned. In the event of an emergency, means for crew
escape is provided by upward ejection seats for those on the upper
deck and downward ejection seats for those on the lower deck. For
those versions of the aircraft in which the gunner was located in
the tail, the entire tall capsule was separated in an emergency
and the gunner was expected to fight his way clear of this unit
and then complete his escape by a hand-operated parachute.
Needless to say, the morale of the gunner was greatly increased
when he was relocated to a position behind the pilots.

With a gross weight of 488 000 pounds, the
B-52H is even today one of the heaviest offensive military
aircraft operated by any nation in the world. Maximum speed of the
B-52H is 639 miles per hour at 20 700 feet, or a Mach number of
0.91, and cruising speed is 525 miles per hour. According to
table
VI, mission radius is 4480 miles
with a weapons load of 10 000 pounds. Many other combinations of
payload and range are, of course, possible. Range is, of course,
greatly increased by in-flight refueling. A B-52 being refueled by
a Boeing KC-135 is shown in figure 12.13. External configuration
of the KC-135 is closely similar to that of the Boeing 707
commercial transport, described in chapter 13.

As an indication of the capability of the
B-52 with in-flight refueling, a nonstop flight of 24 325 miles
was made around the world in January 1957. The flight required 45
hours and 19 minutes. The unrefueled range of the aircraft may be
judged by the world-record nonstop flight of 12 532 miles made by
a B-52H on January 10 and 11, 1962. Average speed for the flight
was 575 miles per hour, and elapsed time was 22 hours and 9
minutes. This world-record flight certainly attests to the high
maximum lift-drag ratio of the aircraft, the low specific fuel
consumption of the engines, and the large fuel capacity of the
aircraft that, in normal operations, can accommodate an
astonishing 47 975 gallons of fuel. (An average American
automobile could be driven 12 000 miles a year for about 80 years
on this quantity of fuel.) Fuel tanks are located in both the wing
and fuselage, and a 700-gallon external tank is carried under each
wing as can be seen in figures 12.9 and 12.10.

[377] The B-52 can
carry a wide assortment of offensive weapons including
conventional "iron bombs," nuclear bombs, and a variety of
missiles such as the ALCM (air-launched cruise missile) and the
SCRAM (short-range attack missile). Four Skybolt ballistic
missiles are mounted on the wings of the B-52H pictured in figure
12.9; this missile was not put into production. Two Hound Dog
missiles are mounted under the wings of the B-52H shown in figure
12.10. The Hound Dog is really a small jet-powered airplane with a
range of up to 700 miles and a maximum speed of Mach 2.1. A more
detailed discussion of the offensive-weapon capability of the B-52
is beyond the scope of the present discussion, as is a description
of the vast array of exotic electronic gear carried aboard the
aircraft.

Thankfully, the B-52 has never been called
upon to deliver a nuclear weapon upon an enemy target. It served
with distinction, however, during the Vietnam conflict. Operating
from bases on the island of Guam, many thousands of tons of
conventional bombs were dropped on targets in North Vietnam. From
Guam to the area of conflict involved a round-trip flight of
nearly 5000 miles. Total mission times were in the order of 16 to
18 hours. Surface-to-air missiles as well as combat with enemy
aircraft were always a possibility in the target area. Certainly,
these missions were a severe test for both men and
machines.

The B-52 was originally designed for
high-altitude weapons delivery over the target. Like the B-47,
however, the increasing effectiveness of enemy antiaircraft
defenses required the development of low-altitude high-speed
penetration tactics for the B-52. Again like the B-47, the B-52
has suffered from its share of structural fatigue problems. To
cure these problems, many modifications have been made to the
aircraft during its long-lived career. But the B-52 lives on and
is likely to form a major part of this nation's nuclear deterrent
force for the foreseeable future.